My Guru Serkong Tsenshab Rinpoche, who was also a guru of His Holiness the Dalai Lama, said that praying to Tara makes it easy to be reborn in the pure land of Avalokiteshvara, the Buddha of Compassion, and receive guidance from him. This is because Tara is close to sentient beings in the way that a mother is close to her children.
If you put your full trust in Tara, you will receive the guidance you need and all your problems will be solved, especially those that relate to each of the 21 Taras, each of whom manifested to alleviate specific problems. Therefore, each of these Taras exists for you.
Even I have experience of this. I once gave the practice of the 21 Taras to a student who had terminal cancer, and with the help of Tara he recovered completely and became a well-known healer.
However, it is your practice of the good heart—cherishing and serving others—that really brings Tara close to you. This is what pleases her most and allows her always to guide you.
Still, the 21 Taras do not exist mainly for temporal success and healing but for the ultimate purpose of freeing you from all sufferings—such as the cycle of aging, sickness, death and rebirth, dissatisfaction, relationship problems and so forth—and their cause: delusion and karma and the negative imprints they leave on your mental continuum, and bringing you to the ever-lasting happiness of liberation and full enlightenment.
Practicing the teachings contained in this book with the intention of reaching liberation and enlightenment will definitely lead you there.